In a rectifying device of a vehicle ac generator disclosed in JP-A-2000-253625 (U.S. Pat. No. 6,198,188), a positive-side radiating fin and a negative-side radiating fin are stacked in an axial direction and a terminal board having connecting terminals is interposed therebetween. Positive-side diodes and negative-side diodes are press-fitted and soldered in through holes provided in both of the radiating fins in the axial direction. The negative-side radiating fin is directly fixed to the outer end surface of a housing with screws and grounded.
When the negative-side radiating fin is fixed to the housing, the negative-side radiating fin is likely to be deformed due to steps on fixing surfaces of the negative-side radiating fin and the housing. As a result, the through holes for fixing the negative-side diodes are deformed and a soldering as a jointing material causes cracks.
In a rectifying device disclosed in JP-A-56-45062, a positive-side radiating fin and a negative-side radiating fin are arranged in one plane surface with a predetermined space. The negative-side radiating fin is directly fixed to the inner wall of a housing forming the outer case of a vehicle ac generator. In this rectifying device, water and the like entering the vehicle ac generator are likely to accumulate and cause corrosion and the like therein.